Jaw crushing apparatus



March 17, 195:3 N;H.BOG1E 2,631,785

JAW CRUSI-IING APPARATUS ATTORNEY March 17, 1953 N. H. BoGlE lJAW CRUSHING APPARATUS Filed NOV. 16, 1949 5 Sheets-Sheet 2 -NE'lSm-L H -Em ATTORNEY March 17, 1953 N. H. BoGlE 2,631,785

JAW CRUSHING APPARATUS Filed Nov. 16, 1949 5 Sheets-Sheet 3 y INVENTOR NElEm-L H Eln iE,

5749 @j Zfwq ATTORNEY' characteristics.

increases the wear upon the jaws.

Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE JAW CRUSHING APPARATUS- Nelson H. Bogie, Lexington, Ky.

Application November 16, 1949, Serial No. 127,651

This invention relates to comminuting apparatus and more particularly to machines for crushing hard and friable materials such as ore, rock, coal and the like. This is a continuationin-part of my co-pending application Serial No. 776,787, led September 29, 1947, which has matured into Patent N o. 2,605,051.

The usual rock crushing machine comprises a hopper-like apparatus formed by a pair of inwardly slanting jaws, one of which is stationary and normally formed integrally with the machine frame, and the other of which is movable through an oscillating path relative to the fixed jaw. In the usual machines, the movable jaw is driven at its top by an eccentric and its bottom is propped by a toggle link so that as the jaw is moved longitudinally by the eccentric, its lower end is moved laterally by the consequent angulation of the toggle. Variations of this structure have been proposed but have proven so unsatisfactory that they are not commercialized and the above described machine is the only one usually seen in actual use.

Despite its more or less general acceptance, this machine has a number of defects and undesirable Due to the action of the toggle,

the driven jaw is moved inwardly when it moves upwardly and downwardly and, consequently, it tends to push the rock to be crushed upwardly instead of feeding it downwardly toward the narrowest, maximum crushing part of the jaws. This action greatly slows the passage of the rock through the machine and decreases production while frequently requiring additional labor to ram the rock down between and through the jaws.

The above described action also has another inherent defect in that the jaws rub and abrade the rock'instead of actually crushing it. This results in the production of a great deal of pulverized material, which is undesirable, rather than crushed material and, in addition, materially Furthermore, even `in the crushed material, non-uniform results are obtained. These defects are increased by the fact that the jaws angle toward each other to their bottom edges so that there are no directly opposed substantially parallel crushing -surfaces to eliminate excessive abrasive action and pulverizing, thereby causing most of the rock or other material to be crushed to proper size.

' Another defect in these machines resides in the fact'that the jaws are not properly adjusted relative to eachother in order to regulate the size of "the crushed'rook. As previously stated, the sta- I tionar'y jawy is fixed as part of the machine frame. rConsequently, to obtain a semblance of adjusta- 2 Claims. (01.241-78) CFI 2 bility, the toggle link of the movable jaw is usually seated against a movable block that is braced relative to the machine frame by shims. By limiting the adjustability to the movable jaw in this manner, the spacing of the jaws is not properly regulated nor lower short nat rock crushing portions in substantially parallel relationv provided, to crush most of the material to size or grade desired instead of excessive pulverization, but only the angulation of the movable jawis varied which results solely in varying the hereinbefore described pulverizing back feeding'and abrasive action.

Still another defect of these prior art machines resides in their inability to produce a uniform crushing effect so that some of the rock has to be re-crushed. In other words, in the rst crushing operation, some of the rock will be reduced to proper size, but other rock which is too large will slip between the jaws or will be abraded or be reduced to too small a size and mostly pulverized. This requires either a screening of the rock and grading or re-crushing the larger rock.

A still further defect in these prior art ma chines resides in the construction of the jaws per se. These jaws usually consist of a frame having one or more wear plates secured to the face of the frame by bolts, screws or the like. These plates wear rather rapidly, due to the above described abrasive action, and have to be replaced frequently. Considerable time is consumed in removing the screws and bolts, however, and, consequently, there is a considerable loss in production' and increase in man hours and expense.

Having in mind the defects of the prior art apparatus, it is an object of this invention to provide a comminuting apparatus which has substantially fiat vertical lower jaw crushing portions movable primarily horizontally toward and away from corresponding coacting stationary jaw portions in the crushing and discharge of the rock, that actually crushes rock and with substantially no abrasive action thereon.

It is another object of the invention to provide a rock crushing machine that has a positive feed action.

It is still another objectof the invention to provide a rock crushing machine that is capable of delivering crushed rock of substantially uniform size to preclude further grading or re-crushing operations.

It is a further object of the invention to provide a rock crushing machine wherein both jaws are adjustably mounted relative to eachother to regulate the size of the crushed rock as desired.

. eration.

It is yet another object of the invention to provide a rock crushing machine wherein the lower crushing end of the movable jaw is movedthrough a crushing stroke toward the stationary jaw only when the movable jaw is not being moved longitudinally.

It is a still further object of the invention to provide a rock crushing machine wherein the lower crushing end of the movable jaw is retracted from the stationary jaw while it is subject to longitudinal movement to preclude abrasion of the rock and to positively feed it.

It is a collateral object of the invention to provide a rock crusher jaw having readily replaceable wear plates to eliminate loss of time and production in replacing these plates.

It is an object of the invention to provide a rock crushing machine having economy of construction, simplicity of design and efficiency of operation.

vThe foregoing objects and others ancillary thereto are. preferably accomplished by a rock crushing-machine having an adjustably mounted stationary jaw, and a movable jaw which is driven at. both its upper and lower ends but in such different directionsand in` timed relation as te accomplish the objects and produce the advantages sta-ted.

According to a preferred'embodiment, the movable jaw comprises a plurality, preferably two verticallydisplacedi crushing jaw portions rigidly connected. to move in unison in the same directions by a laterally inclined screen or bar grizzly to sift the smaller rock after the first crushing operation by the upper jaw and passing the larger rock tothe lower jaw for a second crushing op- In this arrangement there are, preferably, two stationary jaws, one for cooperation with each of the movable jaw portions.

Thev upper drive'for the movable jaw may comprise an eccentric which imparts longitudinal movement tothe jaw with relatively stationary periods between the longitudinal movements whilethe eccentric is passing over and under its pivotal center. The lower drive imparts a horizontal reciprocal movement to the bottom ofv the jaw and is timed to move the jaw toward the stationary jaw or jaws during the relatively' stationary periods and retract the movable jaw during the longitudinal movement periods. The lower drivepreferably comprises an eccentric that rolls freely against the bottom outer surface of the movable jaw and is preferably driven at twice the speed of the upper eccentric so as toA impact the rock twice during each revolution of the upper eccentric.

Each stationary jaw, preferably, .is pivotally mounted at its upper end and propped by an adjustably positioned toggle whereas the lower ec- .centric on the movable jaw is adjustably positioned to vary the position of this lower end of the movable jaw. In order to permit ready replacement of the wear plates, they areV formed in units and adapted to be positioned by a single clamp.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objectsA and advantages thereof, will best be understood from the following description of atspeciiic embodiment when read in connection with the accompanying drawings, whereinlilre reference characters indicate like parts through- Outand in which;

Fig. l is a cross-sectional View taken vertically through a rock-crushing machine in accordance with the present invention;

Fig. 2 is a cross-sectional View taken on line 2 2 of Fig. l;

Figs. 3 and 4 are fragmentary plan views of two modifications of the screening or sifting member between the jaw portions of the movable jaw member;

lfig.A 5 is a cross-sectional View taken on line 5-5 of Fig. 3;

Fig. 6 is a fragmentary exploded view in perspective of the preferred form of bar grizzly;

Fig. 7 is a fragmentary side View in elevation showing the adjustable mounting of the lower eccentric shaft; and y Eiga 8,. 9, 10 and 11 are diagrammatic views illustrating the operation of the movable jaw.

Referring now to the drawings, and specincally with reference to Figure l, a. rock-crushing machine, in accordance with a preferred embodiment of the present invention, comprises a frame i@ including end walls ll, a front wall. l2 and a rear wall i3. The walls are heavily reinforced by ribs i4 to provide a rigid, strong construction that willwithstand the vibration and hard use. to which such machines are subjected. The top of the frame lli is open to receive rock to be crushed, and the bottom ofthe frame .is open .to discharge crushed` rock.

A pair or pairs of crushing jaws are mounted within the frame lf3 and extend between the end wells il thereof. One of these jaws i6 is a movable jaw comprising two jaw portions la and it?) which are stepped or offset with an intermediate screen or bar grizzly Ic. The other jaws i5 and i5 are stationary jaws for respectively cooperating with the jaw portions 16d and i513. These jaws .angle apart toward their upper ends to forma hopperforreceiving the rock to be crushed .therebetween-and include elongatedV flat portions, E'l--'l and l8-I8- respectively, which are angularly arranged to form the hopper. At their lower ends they each include short flat portions ISI-i9 and 21B-25J respectively., which are angnlarly arranged, preferably at obtuse angles, relative to `said elongated hat portions of the jaws so as to be substantially .parallel with each other to provide directly opposed crushing surfaces which are arranged in a substantially vertical position.

The stationary jaws l=5'-I5 each comprise a frame .2| having a recess 22 for receiving the usual wear pla-tes 23. Whereas the usual stationary `jaw is formed integrally with the machine f-rame, one of the advantages of the present invention resides in the fact that the stationary jaws l-l Yare each adjustably mounted within the frame l0. Ela-ch jaw frame 2l has` a boreI 2'4 extending longitudinally through its upper end to receive and. be sup-ported by ashaft 25 which vhas its ends supported by the end walls Il of the machine iframe lll. Consequently, the jaws It-I5 may be pivo-tally adjusted .about their'respective shaft 25 to vary the respective angular position relative to the movable jaw F6.

To regulate th-e position of the jaws l5-l5', they are each provided with a groove 26 in their lower rear surface to form a seat for onel end of a respective toggle 21 which has its other end seated in a groove 28 formed in a block 29 that is adjustably positioned relative to the inside of the front wall l-2 by a plurality of shims 30, the blocks 2S and shims 30 being respectively mounted on ledges 30 extending inwardly of the front wall L2 of the machine frame l0. The jaws are each the screen section |30.

` bars'.

held rigidly against their toggles 21 by a respective tie bOlt 21.

I'-I5 during normal operation but will release the jlaw in the event of a jam or other abnormal operation to prevent damage to the machine.

The movable jaw I 6 is similar to the stationary jaws in that it comprises -a frame 3| that has an offset portion 3| forming a rigid angul-ar open frame-like connection between the spaced upper and lower jaw portions |6a and I6b, for the inf term-ediate screen or bar grizzly I6c and the usual seats 32 for Wear plates 33 defining the jaw portions ISa and Ib respectively above and below The rigid offset open frame-like screen portion or screen holding connecting portion 3|' is inclined inwardly or forwardly between upper end lower jaw portions I'6a and ISb, in obtuse-angled relation thereto, or directly and specifically so related to the lower vertical portion of portion ||6a bearing jaw portion 20 and the upper elongated flat portion |8 or portion I6b Iwhere it angles into portion 3|' in zig-zag formation. In order to facilitate rapid replacement of the wear plates 33 they are each formed as'two separate plates having opposed angular surfaces 34 for engagement by a wedge clamp 35 which may be carried by a bol-t 36 that may extend through the face of the frame 3| and be secured by a nut 31. The respective faces of the wedges 35 preferably coincide with the wear faces of the wear plates 33 and also form Awear surf-aces.

The lower of each of the wear plates 33 preferably includes an angular portion to form the crushing surface 20. Although this mounting of the wear plates is shown only with respect to the movable jaw I6, obviously this construction may be incorporated in the stationary jaws I5-I5.

',Ihe offset portion 3|', as shown in Figs. 1, 3 and 4, has a through opening 'I5 with recesses ralong the two transverse edges to provide ledges crossed bars, with the ends in either case resting on the led-ges lis. The screen 'I'Ia must be formed as a unit but a plurality of units with different rsizes of mesh may be provided. The bars 'I1 may be rigidly secured together as a unitary structure but, prferably, the bars 1I are independent so that they may be selectively spaced to provid-e slot openings -therebetween of desired width. The units or independent bars 'I'Iare of a height equal to the height of the ledge recesses so that the tops of the bars are flush with the top surface of the frame portion 3 I In the case of the independent bars Tf1, their ends are notched between their top and end edges to provide end portions 'II' which, preferably, comprise semi-dovetails as their top edges are incl-ined downwardly. Spacer blocks 'I8 are positioned on the ledges 'I3 between the end-s 'II of adjacent bars 'I'I to thereby selectively space the The t-op surfaces of the spacer blocks 'II8 are inclined downwardly to coincide with the top edges of the bar end portions TI', the blocks 'I3 having a cross-section corresponding to the profile of the end portions 'I1'.

AClamp bars 'I9 overlie the respectiveV end portions lland spacer blocks 718. The clamp bars 'I9 have inclined bottom surfaces to coincide with the inclined top surfaces of the blocks 'I8 and end portions I'I' and the bars 'I9 are of a cross-section to lill the recesses between the opposed walls of the frame and the upstanding offset edges of the grizzly bars 'II so that the tops of the clamp bars 'I9 are flush with the surface of the frame portion V3 I and the top edges of the grizzly bars.

The clamp bars 'I9 are secured by spaced bolts 8l) which extend through the bars T9, Vunderlying spacer blocks 'I8 and are threaded into the frame portion 3|', the bars I9 being countersunk to receive the heads of the bolts 80 s-o that the surface of the grizzly section is smooth and unbroken by protrusions. Th-e inclined bottom surfaces of the clamp bars I9 cooperate with th-e inclined upper surfaces o-f the spacer blocks I3 to wedge or lock said blocks on the ledges TIS between the grizzly bars 11. The said abutting or cooperating surfaces may be parallel to the top and bottom surfaces'instead of inclined, but in this event, ad-

ditional locking means for each spacer block 'I8 is necessary, such as bolts 80 extending through the clamp bar I9 with one of the bolts extending through each spacer block.

A chute 8| is mounted within the main frame with its open upper end 32 disposed beneath the through opening 15. The chute may be attached directly to the underside of the frame portion 3|' t-o form a closed disch-arge passage, but in which event it would move with the movable jaw I6. As such movement is not desirable, however, the chute 8|, preferably, is rigidly supported between the side frames I and pro-vided withV a mouth or open upper end 32 that is spaced from the underside of the frame portion'3l to permit the relative movement of the jaw, but is extended in size to underlie the discharge end of the grizzly opening I5 throughout the path of movement of said opening during th-e movement of the jaw.

The movable jaw IB is mounted atits top on an eccentric in the usual manner, the frame 3| having a sleeve 3B at its upper end to receive the outer race 39 of an antifric-tion bearing 40, the inner race 4I lof which surrounds an eccentric 42 formed integrally with a shaft A43. Obviously, the eccentric need not be formed integrally with the shaft 43 but may be keyed or otherwise mounted thereon, and, if desired, a crank'may be substituted for the eccentric. The shaft 43 is journalled in the end walls II of the machine frame I and may carry a fly wheel 4'4 and be driven in any suitable manner. Y y

The lower ends of the jaw frame 3| at the seats 312 are angularly positioned to accommodate the crushing faces llz and the rear side of the bottom of th-e frame 3| opposite the face 20 is provided with a bearing surface 45 which, preferably, is formed by a hardened metal plate 4B seated in a recess 4l in th-e frame 3|. The surface 45 of the plate 46 bears against the outer race 43 of an antifriction bearing 49, the inner race 53 of which is mounted on an eccentric 5| carried by a shallt 5,2 that is journalled in the end walls I I of the machine frame I0. A-s a matter of convenience and economy, the upper and lower shafts 43 and 52, eccentrics 42 and 5|, and bearings 40 and 43 may be identical in size.

The shaft 5'2 'is driven in order to impart a lateral movement to the crushing faces 23-20 and, preferably, this shaflt is driven from and in timed relation with the upper driven shaft 43. This may be accomplished by any suitable means,

and for purposes o-f illustration, is shown as comprising a chain drive, although a. gear or other lower shaft 52.

vsaid vend walls I I.

Adrive may be used.' A sprocket 53 is fixed on the shaft v43 to be Vdriven therewith and a chain 54 is trained around the sprocket 53 and another sprocket 5'5 which is como-unted with another sprocket 55 on a shaft 55a supported by one of the end walls I l of the machine frame I0. A sec- `ond` chain 54 is trained around the sprocket 5.5 and another sprocket 56, that is fixed on the The chain drive preferablycomprises a reduction so that the lower shaft 5'2 is driven` at a higher rate of speed than the shaft 43, ,preferably at the rate of 2 to 1. It will be noted that asv the shaft 52 is driven it will revolve the eccentric 5I and bearing 49 so that the outer race 48 will roll up and down on the bearing surface 45 of the wear plate 4S while reciprocating the crushing surfaces .2 -2 Il Although the lower end of the jaw I 6 will tend to follow the reciprocal movement of the outer f race 48 due to gravity, it is p-referred to positively maintain vcontact between the surface 45 of the bearing plate lt6 and th-e periphery of the race 4S. This may be accomplished by one or more pull rods 51 that may be connected to the jaw frame 3! and, according to the modification shown, a pull rod 51 m-ay be provided for each side Yof each of the jaw portions Itc--IBb to provide uniform tension, the rods for the lower jaw portion ISb lying on each side of the chute 8l. Each rod is connected by a pivot 58 mounted in a bracket 59 carried by the frame 3I, and extends rearwardly through an aperture B0 and socket 6I in the rear wall I3of the machine frame I0 and preferably extends beyond said rear wall I3 for a short dis- A helical spring,r 62 biases each pull rod tance. 51 outwardly to pull the jaw I6 against the race 48, the' spring 62 surrounding the rod 51, seating in the socket 6I and bearing against a collar 63 and nut 64 'threaded on the rod 51 for adjustment of the tension of the spring and biasing action thereof holding the surface 45 of bearing and wear plate 4B against race 48.

In order to effect adjustment of the lower end of the movable jaw IIS it is obvious-ly necessary to adjustably mount the shaft 52 in the en-d walls II of the machine frame I0. Consequently, the ends of the shaft 52 are preferably seated in bearings 65, preferably anti-friction bearings, which may be seated in corresponding slots 65 in Depending upon the type o-f drive system employed, the slots 65 are preferably arcuate and are pro-vided with means for adjustably positioning the bearings Y55 therein. In the present instance, as best sho-wn in Fig. 7, the slots 56 are `curved on a radius from the axis 55a, of the sprocket 55 so that the sprocket 56,

on the shaft 52, may swing with the chain 54' about the shaft 55a, when the bearings 65 are adjusted in the slots 615. The ends 51 of the slots 66 are preferably parallel in o-rder to flatly engage shims 58, a plurality of the said shims 68 being inserted in the slots EIB as desired on either o-r both sides of the bearings B5.

In assembling the machine o-f the present invention the shafts 43 and 512 are preferably arranged so that their respective eccentrics 42 and I have a predetermined relationship when said shafts are driven. This is desirable in order to lobtain maxi-mum operating efficiency, a posi-tive feed to the crushing surfaces I9-I 3 and 20--20, and to eliminate unnecessary abrasion of the wear plates 23 and 33. I-t is preferred that the relationship be such that `the lower eccentric 5I will act to move the crushing surfaces -20 toward their opposed surfaces I9-I9 only'when Y the up-perfecc'entric 42 passing througha crossthe rock.

The labove described operation has the additional advantage of positively feeding `the rock to the crushing portions I9-I-9 and 20-20 so -that theA rock will never jam or need additional means for maintaining an even flow through the machine. This action is effected by the retraction ofthe lower portions 20-20 duringr the longitudinal movement of 'the jaw I5 so that the throats V`IiP-2f), ISL-20" of the jaws are enlarged whenever there is a longitudinal agitation of the rock therebetween. Therefore, when the rock is loosened by longitudinal agitation, it is free to gravitate between. the expanded crushing portions.

Furthermore, they movement of the jaw IG-is preferably effected in such a manner as to obtain maximum Vfeeding action by driving the upper eccentric 42 in a` direction so that it moves downward when passing through its forward position so that the rock receives a positive downward movement when the upper portion of the jaw I5 passes through its forward position so as to positively push the rock down between the expanded portions I9-I9 and 2li-20. Consequently, the jaw I6 is moved upwardly while passing through its rearward position so that it is at its maximum spacing from the stationary jaws I5-I5' and thereby permits the readysettling of the rock, the upward movement imparted to the rock adjacent the jaw I 6 merely serving to agitato the impacted rock 'to promote its settling.

The hereinbefore described action of the jaws is diagrammatically illustrated in Figs. 8 thru 11, the jaw I5 being in a constant position throughout thesel diagrams. Fig, 8 illustrates the jaws and eccentricsin the same position as that shown in. Fig. 1 and this position will be employed as a starting point in describing the cycle of operation, the shafts 43 and 52 being driven in the direction of the small arrows associated therewith, according to the preferred operation of the invention` In the position of the apparatus shownin the drawings, the shafts are preferably driven counter-fclockwise.

Referring specifically to Fig. 8, it will be seen that the upper eccentric 42 is in the center of its forward position and, preferably, is in its downward stroke. Consequently, the jaw I B is moving downwardly, as indicated by the downward, vertical arrow V, and the upper end of the jaw is in its extreme forward position. Simultaneously, the lower eccentric 5I is in the center of its rearward movement, so that the crushing portions 2li-20' are retracted to their extreme rearward, open position as indicated by the horizontal, rearward arrow R. Therefore, as the jaw I 6 is moving downwardly with its upper end in forward position it will tend to push the rock down between the open crushing portions IQ-IS and 2li-20'.

It will be understood that Vduring the longitudinal movement of the jaw I5, its lower rear bearing surface 45 will travel over the periphery 48 of the lower bearing 49, the periphery or outer race 4I8 merely rolling along the reciprocating surface .position due to the 2 to 1 reduction drive therebetween. When the upper eccentric passes through its downward position the longitudinal movement of the jaw I6 is, for all practica1 purposes, substantially ceased and instead a lateral horizontal movement is imparted to the upper end of the jaw IB as indicated by the rearward, horizontal arrow H. During this period of substantially no longitudinal movement of jaw IB the' lower eccentric 5| is operated to impart a lateral, horizontal forward or inward movement to the lower end of the jaw I6 to deliver the forward, crushing stroke to the crushing portions 24J-20', as indicated by the horizontal, forward arrow F. Thus, the crushing stroke is delivered while the jaw is devoid of longitudinal movement eithei` upwardly or downwardly so that there is substantially no rubbing abrasion of the rock or wear plates 33 to substantially reduce or eliminate pulverization. Y

WithV continued rotation of the upper shaft 43 a quarterv revolution its eccentric 42 passes outwardly or rearwardly beyond its cross stroke to its extreme rearward position, as shown in Fig. 10, while moving upwardly. Consequently the jaw I6 receives an upward, longitudinal movement as indicated by the upward, vertical arrow V. Therefore, the lower shaft 52 simultaneously rotates half a revolution to revolve its eccentric 5|` to its rearward position to retract the crushing portions 2li- 20' as indicated by the horizontahrearward arrows R. Thus, while the jaw I6 is moved longitudinally upwardly the crushing portions are again opened so as to avoid abrasive pressure on the rock and wear plates and permit settling of the rock between the crushing portions lli-I9 and 20-20'. Furthermore, as the upper end of the jaw I6 is retracted while moving upwardly, the rock mass is permitted to expand and settle rather than to be fed backwardly as in the prior apparatus. As a matter of fact, the upward movement of the jaw is imparted only slightly to the rock in immediate contact therewith and this movement has the advantage of agitating the rock mass and thereby promotes settling of the mass.

Continued rotation of the upper shaft 43 a quarter revolution revolves its eccentric 42 to its upper position, as shown in Fig. l1, whereupon it is in the midst of its forward or inward crossstroke, as indicated by the forward horizontal arrow H', and longitudinal movement of the jaw I6 is ceased. Simultaneously, the lower shaft 52 rotates a half revolution to revolve its eccentric 5| forwardly or inwardly to impart a crushing stroke to the portions -20' as indicated by the horizontal forward arrows F. Thus, the crushing stroke is again delivered while the jaw I5 is free of longitudinal movement. Continued rotation of the shafts 43 and 52 moves the jaw I6 into its downward, open-throated feeding position which is, shown in Fig. 8 and completes the cycle of operation.

In view of the foregoing description, it will be seen that the crushing portions 20-20 deliver K a crushing stroke twice during each cycle of operation of the jaw I6, that is, for each revolution of the shaft 43 as well as a retracting stroke twice during such cycle, as described. The speed of operation may be varied through a relatively wide range; however, it is preferred that this speed should be regulatedY within specific limits or at least above a certain minimum. More specifically, it has been found that superior results are obtained if the rock receives two impacts while gravitating between each of the crushing portions I-Z and |9-2D.

To graphically illustrate, a piece of rock X is shown .at the entrance of the crushing throat ISB- 20 in Fig. 8. Between gravity and the feed-4 ing and settling action of the jaw I6, this rock X is delivered into the upper end of the throat Ill-2Q and impacted therein, as shown in Fig. 9, to break or crush it into pieces When'the throat IEB-29 is again opened, the pieces gravitate and are fed downwardly as shown in Fig. 10 and are again impacted in the lower end of the throat Isl-2c, as shown in Fig. 11, to further crush it to approximately the desired size.

The crushed rock n; then gravitates from the crushing portions |9-20 onto the screen or bar grizzly |50 where that part of the rock that has been crushed to the desired size Will be sifted and will drop through the screen into the chute 8| and discharged as to a conveyor C, as illustrated by the rock az in Fig. 10 and as also shown in Fig. 1. The larger rock that cannot pass through the screen will roll or slide down the incline of the screen Ic into the lower set of jaws |5-|6b where the rock again receives about two crushing strokes while passing between the portions |92U where it is further crushed to provide rock x of the desired size, after which it is also discharged, as to the conveyor C.

By this arrangement, the rock X is crushed to provide crushed rock of substantially uniform size and with a minimum of waste in dust and chips.

the portions Ill- 25, this rock is not subject to pulverzation in the subsequent crushing operation. Furthermore, the rock need not be crushed.: i;

as heavily in the rst operation as is necessary if the rock is crushed in a single operation, as the portions |9-2 may be spaced further apart than the jaws I5-2ll. In addition, even though the rock is subject to two operations and passes between two sets of jaws, according to the present invention, there is only one movable jaw and only one drive mechanism.

In a preferred size and form of machine it has been found that if the shaft 43 is driven at 200 R. P. M. and the shaft 52 at 400 R. P. M., the rock falls about 4 inches between impacts or during a complete cycle of operation. Therefore, it has been found that the crushing portions |9-|9' and 2li-20 obtained the desired results when they are about 6 inches in height. Obviously, the rock may be impacted more than twice but this action is not necessary as the desired results are obtained, for all practical purposes, by a double impact and the excessive wear on the machine due to a higher rate of operation more than offsets any advantage. In addition, it is evident that the invention may be practised with two movable jaws in lieu of one movable and one stationary, with both movable jaws operating in the manner of the herein-described jaw I6. However, the use of the stationary jaw l5 is By removal of therock which is crushed to proper size in the first crushing operation by preferred so as to simplify and economize on construction and operation while obtaining substantially equally satisfactory results.

YIt will be understood that the present invention `is equally adaptable for crushing ore, coal or other friable materials although described herein as a rock crusher.

Although a certain specific embodiment of the invention has been shown and described, it is obvious that many modications thereof are `pos,- sible. The invention, therefore, is not to be restricted except in so far as is necessitated by the prior art and by the spirit of the appended claims,

* Ihat which is claimed as new is:

1. n rock crusher comprising a base frame having two crusher sections, one above the other, a p air of opposed jaws in veach of said Crusher sections, each said jaw having an inclined portion cooperative with the opposed jaw and said base frame to form a hopper and a substantially vertical portion cooperative with the opposed jaw to form crusher portions, one jaw of each pair being mounted 'in said base frame in independently adjustable stationary relationship, a single jaw frame extending through both of said crusher sections and carrying the other jaw of each pair, an eccentric journalled in said base frame and pivotally supporting the upper end of said jaw frame adjacent the upper end of the upper ofthe jaws carried thereby, said jaw frame being oiiset between the lower end of the upper jaw and the upper end of the lower jaw and having a passage through said offset, a screen mounted across said passage substantially flush with the surface of said olset, a lower rotatable eccentric means journalled in said base frame and slidably engaging the lower portion of said jaw frame behind the crusher portion of the lower jaw carried thereby, means between said jaw frame and said base frame and resiliently retracting said jaw frame against said lower eccentric means, and means for driving said upper eccentric and lower eccentric means and including means correlating therate of the lower eccentric means at a two,- tofone ratio relative to the rate of said upper eccentric and with the eccentric portions thereof in uniform angular relation about their axes.

I2. VA rock Crusher as defined in claim' 1 wherein said `jaw frame offset has recessed ledges on kopposite sides of said passage and said screen comprises a plurality of grizzly bars mounted in spaced parallel relation on said ledges and spanning said passage, said grizzly vbars having acute angle notches in their upper corner portions, spacers on said ledges between the ends of said grizzly bars and having inclined upper surfaces corresponding to the angularly disposed edges of the notches, retainer bars overlying said edges and mounted inlsaid notches and on said vspacers and having an inclined bottom surface mating with the LSpacers and notch edges, and means securing the retainer bars in position to lockA the grizzly barsin place.

' NELSGN H. BOGlE.

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